Number of double cosets of the Sylow 2-subgroup of the symmetric group S_n.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =4a(5) =8a(6) =35a(7) =16a(8) =51a(9) =145a(10) =1112a(11) =1145a(12) =10929a(13) =41400a(14) =542785a(15) =40384a(16) =583169a(17) =2781808a(18) =48558706a(19) =65461347a(20) =1277941540a(21) =7370563251a(22) =159694747220a(23) =63387056365